The fit between the jaws is restored by riveting pieces of sheet brass to that side of the brasses that has worn the most (usually the top which carries the weight of the rod). [Fig. 2396] shows this operation carried out, a being the pieces of sheet brass which are sometimes soldered as well as held by rivets. These rivets are screwed into the brass, being composed of softened brass wire riveted after being screwed in.
If these pieces, which are called liners, are placed on the top of the brasses at one end, they should also be placed at the top of the brasses at the other end of the rod. They should not be less than about the 1⁄24 inch thick, the body of the brass being cut off to admit them if necessary.
In filing the joint faces of the brasses to let them together so as to take up the lost motion due to the wear of the brass bore and of the crank pin, the following considerations are met.
Fig. 2397.
Fig. 2398.
If the brass faces are to come “brass and brass,” that is, butt together, when their bore is of the diameter of the journal, file those faces away until the bore appears just perceptibly too large for the journal, when measured with calipers, as in [Fig. 2397], the bore measuring parallel all the way through. But, in doing this, it is necessary to be careful to file each brass so that it shall embrace one-half the journal diameter, which will be the case when the two brasses measure correctly as above, and alike, when tested, as in [Fig. 2398], in which p is a planed surface, c a pair of inside calipers, and b a brass resting on p. When filing the joint faces, test them with a square as in [Fig. 2399], in which s is a square and b a brass, and also in [Fig. 2400], in which s is a square and b the brass shown in section, thus making the faces quite square.